NATO is now tram connected, so don't look along 12 route. Tram 62 to Meiser, then tram 7/25 goes through Montgomery - to there is about 20 minutes from NATO.
Another good route is 62 tram to Da Vinci then 80 bus which wanders through WSL to Montgomery and further into Etterbeek.
Another good route is 62 tram to Lekaerts then 45 bus which also wanders throug WSL and terminates at Roodebeek metro.
If you look at those 3 routes, that area is mainly WSL but some is Etterbeek, WSP, even Schaerbeek.
I'd avoid Schuman to live because the housing is far higher priced due to proximity of the EU buildings and it will take longer to get there and no private schools and the public schools are going to be difficult at this stage to get places unless you go for les Eburons maternelle.
There are a few public schools I'd look at :
Bonheur
Sacre-Coeur de Lindhout
Divin Sauveur
Angelus
Bemel
Paradis des Enfants
EOS - a Steiner school at Montgomery, very interesting, open evenings soon, small voluntary fees
Singelijn - near Roodebeek metro, lots of kids of NATO/EU, small voluntary fees
As for private schools :
BISB - at Meiser where the 62 tram goes off west, only English
BJAB - at Montgomery, only English
Montessori House Brussels - French / English but very few French speaking kids, very small school so might be full
International Montessori X 2 - a bit north of Roodebeek metro, French / English, might give you a bit more exposure to French, one place does 2-6 only, the other goes to age 18, should have spaces
All those schools are frightfully expensive. They are the 4 I would stick to, for work near NATO.
Having written all that, I think personally I'd be looking at living at 1) within 500 metres of Montgomery metro/tram or 2) easy reach of Roodebeek metro
I've known children keep their French after 3 years here, it's up to you if you end up somewhere not French speaking how much effort you put into it. It's always there though, it's quite a positive, it can be picked up in a later life. Many people stay much longer than a few years, when they initially arrive for a short period.
I'm in a group which has helped many families to move to Brussels. I love house hunting from my laptop. Longtimeinbrussels is the person to contact or you can pm me, as our group is on facebook and it's a secret group.
Take a look at the STIB plan which shows the 62 tram and the connecting trams 7/25 and buses 80 and 45.
www.stib-mivb.be/article.html?_guid=00266bf9-0883-3410-bc80-cd51a4d340c3&l=fr#contentBodyList0